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INTERNAL COMBUSTION ENGINE Original Filed March 7, 1946 15 Sheets-Sheet 15 F 1 i j W 5 53 Q llll 1| 8 Ti 2 H .G I 1 M4. I a 6 g I 4% Z U Q o 5 a e 4 4 United States Patent INTERNAL COMBUSTION ENGINE John L. Hittell, Livonia, Mich.

Original No. 2,644,021, dated June 30, 1953, Serial No. 652,678, March 7, 1946. Application for reissue December 9, 1954, Serial No. 474,310

31 Claims. (Cl. 123-48) Matter enclosed in heavy brackets II] appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

This invention pertains particularly to structures cooperating to improve efiiciency, durability and adaptability of [such] internal combustion engines by providing means for successful operation at variable displacement, and for improved compression ignition operation.

One object of this invention is to provide automatic means for controlling the variable displacement of the engine and to have this means operate in accordance with the amount of power the engine is being called upon to produce by the combined action of the operators control of the throttle and the load on the engine.

It is a further object to provide speed limiting control devices capable of limiting the engine speed to a certain value at full displacement but allowing increase of this speed in accordance with increase safe operating speed at reduced displacement and speed responsive means for advancing injection timing as the engine speed is increased and to provide an engine with novel valve mechanism capable of satisfactory and enduring operation at ultra high speeds when operating the engine at reduced displacement.

Another object of this invention is to provide improved means of fuel injection capable of maintaining an ultra fine degree of atomization even at cranking speeds and also capable of metering the fuel injected per cylinder stroke in more exact proportion to the weight of air taken into the cylinder under wide variations of operating conditions.

A further important object of this invention is to provide means for maintaining consistent accuracy of fuel metering under variations of fuel viscosity and wear of parts by completely eliminating leakage through sliding or running fits as a factor affecting fuel metering, and further to avoid likelihood of the fuel becoming mixed with lubricating oil by avoiding any reliance on the ability of any rotating or sliding fit to keep the fuel and lubricating oil separated. These two features avoid the need of ultra-fine fits heretofore found to be absolutely necessary in high pressure fuel injection equipment and usually a cause of high manufacturing costs and considerable service trouble on account of sticking due to microscopic dirt particles, thermal expansion, surface growth or even slight gum or lacquer formation, or leaking beyond a tolerable amount due to even very slight wear.

Other objects are to provide fuel injection means unusually free from external piping and high pressure joints, to provide short lines free from harmful resonant conditions even at ultra-high operating speeds, and to provide for removal of injectors for test or replacement without disturbing any piping.

A further object of this invention is to widen the range of fuels which can be used with full satisfaction in a compression ignition engine by providing an injection system able to properly meter and atomize fuels of widely differing distilling ranges, even as light as gasoline, and to handle fuels of low ignition quality by operating at high compression pressures and temperatures and by mainice taining fine fuel atomization under all operating conditions, especially at cranking speeds.

A more general object of this invention is to provide numerous new features contributing greatly to overall performance, long life and easy servicing of internal combustion engines and to devise and combine same in such compact, light weight and economical-to-manufacture form and arrangement that the savings thus accrued make possible the inclusion of these numerous improved features without increase in cost.

Further objects of this invention are such as may be attained by utilization of the various combinations, subcombinations, and principles hereinafter set forth in the various relations to which they may be adapted without departing from the spirit of my invention, as set forth more particularly in the following detailed disclosure of the preferred embodiments and in the terms of the appended claims.

Referring to the drawings:

Fig. 1 is an exterior plan view of the engine showing also, somewhat diagrammatically, the principal accessones.

Fig. 2 is a vertical section through the complete unit along line 2-2 of Fig. 1. Certain parts having the interior detail too fine to show clearly in this figure are shown in exterior view and shown in detail sections to a larger scale in other figures.

Fig. 3 is a partial horizontal section stepped as indicated by line 3-3 of Fig. 2.

Fig. -4 is a partial vertical section through the lower portion of the mechanism as indicated by line 4-4 on Fig. 3.

Fig. 5 is a vertical section through the lower portion of the mechanism, along line 5-5 of Fig. 3.

Fig. 6 is a horizontal section through a lower portion of the engine along line 6-6 of Fig. 5.

Fig. 7 is an enlarged partial section through the engine base along line 7-7 of Fig. 3 and 2-2 of Fig. 1 showing detail not shown in Fig. 2.

Fig. 8 is an enlarged vertical center line section through the fuel pump along line 8-8 of Fig. 3.

Fig. 9 is a vertical center line section through the fuel control box along the radial line 9-9 of Fig. 1.

Fig. 10 is a horizontal section through fuel control box substantially along line 10-10 of Fig. 9.

Fig. 11 is a vertical section through the fuel control box along line 11-11 of Fig. 9.

Fig. 12 is an end view of the extending portion of the fuel control box viewed as indicated by the line 12-12 of Fig. 9.

Fig. 13 is a view of some of the fuel box parts removed from the rest of the mechanism.

Fig. 14 is a stepped horizontal section through the engine head along line 14-14 of Fig. 2.

Fig. 15 is a vertical partial section through the engine head along a radial line 15-15 shown in Fig. 14. This is a typical section repeated in most respects in 6 other corresponding positions. The variations involved are shown in other views, particularly in Figs. 1, 2, 9, and 14.

Fig. 16 is a horizontal section through the top portion of the engine along line 16-16 of Fig. 2.

Fig. 17 is an enlarged partial vertical section substantially along line 17-17 of Fig. l. The governor mechanism is here seen cut ata right angle to the way it is shown in Fig. 2.

Fig. 18 is a partial horizontal section showing detail along line 18-18 of Fig. 2.

Fig. 19 is also a partial horizontal section showing detail along line 19-19 of Fig. 2.

centerline of the injector showing detail omitted from Figs. 2 and 17.

Fig. is a view of a modified form of injector and injector shell.

Fig. 26 is a sectional view through centerline of same as indicated by line 2626 of Fig. 25.

Fig. 27 is a partial view and section along line 2727 of Fig. 2.

Fig. 28 is an enlarged partial section along line 22 of Fig. 1 showing details of rings, and upper connecting rod end ball joints, and showing also a modified form of piston particularly suited to this engine.

Fig. 29 shows a section along line 2929 of Fig. 28.

Figs. 30, 31, 32, and 33 show further enlarged sections along lines indicated by corresponding numbers in Fig. 29.

Fig. 34 is a section through the injector shown in Fig. 24 along line 34-34 of Fig. 24.

Fig. is a partial section along line 3535 of Fig. 8.

While various important novel features of this invention can be usefully applied to engines of any known form or arrangement, an engine embodying all of the features of this invention in combination takes the form of a four-cycle compression ignition engine with a central shaft, preferably vertically disposed or substantially so, and with an odd number of cylinders arranged in a circle about the main axis and approximately parallel thereto.

Such an engine in small sizes may preferably be embodied in three cylinder form, while for engines of intermediate sizes such as are commonly used in self propelled road vehicles a seven cylinder construction is preferred and selected for illustration in this preferred embodiment, while for other uses five or nine or more cylinders might be more suitable.

In the seven cylinder engine herein described in detail and shown in the drawings, a base casting 1 serves as a general framework and housing in or upon which most of the apparatus is mounted. Referring initially to Fig. 2, an engine cylinder block 2 is mounted on the base 1 and retained thereon by cap screws 1a. The cylinder block carries liners 3 suitably fitted in the block at the top and bottom. Pistons 4 reciprocate in these liners and carry rings 5 for sealing the compression and firing pressures.

Tubular connecting rods 6 each have two cupped ends accurately finished inside and out to form concentric spherical surfaces. The lower end of each rod rests on a pressure block 7 and is held by retainer 8. The retainers and pressure blocks each have spherically finished surfaces mating with the spherical surfaces of the rod end to form a spherical bearing permitting the rod to swing to a limited angle in any direction. The blocks 7 rest on the upper plane surface of a rocking member 9 and are held against shifting by means of integral tubular extensions 10 proiecting upward from the plane surface of member 9. The retainers 8 also rest on the plane surface of rocking member 9, and are held thereto by bolts 11. A similar type of joint at the upper end of the rod allows same to also swing at limited angles to the axis of the piston in any direction.

A displacement control member 12 is slidably fitted in a large bore in base casting 1 and has a smaller diameter portion extending downward into and also slidably fitting in a smaller bore in this casting. An annular piston 13 is aflixed to the displacement control member by cap screws 14 and is slidably fitted in a larger bore in casting 1 and sealed by a ring 15. A ring 16 also seals the large diameter portion of control member 12 to complete the sealing of an annular chamber 17. When oil under pressure is admitted to chamber 17 it thus tends to raise the control member toward its uppermost position, in which it is shown.

Formed integrally with the upper end of the control member 12 is the inner member of an improved type of constant angular velocity universal joint. A number of ball races 12a are formed in the periphery of this portion with lands between these races forming partial spherical surfaces concentric with the point X and also with the main vertical axis. A thrust and centering member 12b is snugly fitted to the extreme upper end of member 12 and has a spherical surface, bearing against a concave spherical washer 18. A ball retainer and aligner 19 has an internal cylindrical surface in rocking contact with a portion of the lands between the said races 12a and a concentric exterior spherical surface in rocking contact with the central portion of the rocking member 9 which also has formed therein internal races 9a for the balls 20. This forms a constant angular velocity universal joint of a general type that is known, but I have devised certain improvements which will be more fully described hereinafter.

It is evident that a geometrically correct constant angular velocity universal joint in this environment serves to permit the rocking member 9 to rock about point X either fore and aft or left and right or any combination thereof without disturbing in the slightest way the angular position of the rocking member 9 about its axis along the line X-Y. The control member 12 and piston 13 are prevented from being rotated by torque reaction by three extensions 13a on piston 13 which register with three bores in casting 1.

Two annular contact ball bearings 21 are mounted on the inner portion of rocking member 9 and retained by nut 22 and lock wire 23, and a flywheel 24 is mounted on the outer races of these ball bearings, and retained in position thereon by cap ring 25 and bolts 26. One end of a link 27 is hinged to flywheel 24 by means of a pin 28 and a pin 29 through the other end of the link and through a shaft 30 hinges the upper end of the link to the shaft 30 on an axis intersecting the axis of the shaft. The flywheel 24 has an internally splined hub mating with an externally splined portion of a shaft 31 and is held in position thereon by a nut 32 which also retains a washer 33 which carries short splines to mesh with those on shaft 31 to hold this washer against turning so that an integral cam portion 34 is held in proper position to enter a slot provided in the link 27. The splines on flywheel 24 and shaft 31 also permit a pin 35. which is fitted in the lower end of the shaft 31 and the upper end of a power take-off quill shaft 37 and retained by lock rings 36, to be held parallel with pins 28 and 29.

It may now be noted that this construction permits the flywheel 24, the link 27, and the shafts 30, 31, and 37 to all rotate as a unit about the axis of shafts 30 and 37. carrying with them, of course, all the directly attached parts. This rotation carries the outer races of the ball bearings 21 in rotation about the main axis also, and since these ball bearings are at an angle, with the high point aligned with the link 27, the rocking member 9 is forced to rock about the point X as the above described parts rotate, with the result that rocking member 9 has its high edge follow around with rotation of the low end of link 27, but does not rotate at all, being held from rotation or even small angular oscillation about its axis X-Y by the balls 20 and their cooperating races. Accompanying this motion of rocking member 9 and pistons recipro' cate in the cylinder liners 3 an amount that is governed primarily by the radius of the lower spherical center lines of the connecting rods 6 from the axis X-Y and by the angle of tilt of the bearings 21.

It now becomes evident that if the point X is lowered, keeping the center line of pin 29 at the same level, the angle of tilt of the bearings 21 is increased, and thus as point X is lowered the stroke of the pistons is thereby increased.

It might at first appear that lowering of point X would caust the upper limit of the stroke to be raised while the lower limit is being lowered, but this is not the case, since as point X is lowered the center line :of pin 28 is also lowered to a lesser degree with the result that the top point of the stroke is made to lower slightly as the bottom point is lowered to its maximum stroke point.

By proper positioning of the pins 28 and 29 in relation to the high and low positions of pin 35, accompanied of course, by suitable length of link 27 and of connecting rods and pistons in relation to piston head clearance, it is possible to hold a compression ratio of 15 to 1 at full displacement and at two-thirds of full displacement and then to have the compression ratio increase to approximately 16 to 1 at one-half displacement and to approximately 20 to 1 at one-third of full displacement.

It has been most simple to explain the action of this mechanism starting from shaft rotation and developing the accompanying piston travel which is of course the true case when starting or when the flywheel is carrynig a cylinder up its compression stroke. However the mechanism is fully reversible and the power of the firing strokes is delivered to the quill shaft 37 simply by reversing the travel of the forces from part to part.

The quill shaft 37 is mounted at its lower end in a ball bearing 38 supported inside the lower portion of control member 12. This bearing serves primarily as a thrust bearing, and is retained by a nut 39 and lock means 40 so that it is able to draw down on the quill shaft 37, and through the shaft 31, flywheel 24 and bearings 21 is able to hold the spherical surfaces of elements 12b and 18 in close running contact so that they serve to center the revolving and rocking mechanism in relation to the upper portion of control member 12. This also centers the shaft 31 and the upper end of the shaft 37, which may have a considerable clearance in the bore of the control member 12.

The quill shaft 37 is slidably splined to the upper portion of a shaft 41. A short quill shaft 42 surrounds and is splined to a lower portion of the shaft 41 and has a spiral bevel gear 43 formed integralyL A small gear 44, carrying a bearing 45 is fitted and splined to the lower end of the shaft 41 (Fig. 5). A nut 46, with lock means 47, holds the gear 44, the bearing 45, and the quill shaft 42 firmly against a shoulder 48 on the shaft 41, thereby positioning the shaft 41 in relation to the shaft 42 which is mounted in a bearing 49. The bearings 45 and 49 are mounted in a bearing plate 50 which is also bored to form a close running fit for the shaft 42.

The bearing plate 50 has ports 51 milled therein, and the shaft 42 cooperates to act as a rotary valve by means of ports 42a (Figs. 5 and 6) -milled therein and a communicating annular port 42b. A pump body 52 fits closely over the hub of the bearing plate 50 and has a gear chamber and a bearing for a gear pump gear 53 which has an integral shaft and is driven by a gear 54 splined thereto and driven by the gear 44. The pump gear 53 meshes with two similar integral shaft pumping gears 55 (Fig. 6), and the gears 53 and 55 are covered and retained by a pump cover 56 which also fits closely on and is located by centering on the hub of plate 50. A pin 57 (Fig. 2) gives the additional locating point required to keep the pump casing parts in full alignment. An outlet passage 58 is cored in the pump body 52 and discharge ports 58a (Fig. 6) provide communication between passage 58 and the chamber in which the pumping gears operate. The

cover 56 has cored therein an inlet manifold 59 and ports which open into the pumping gear chamber. Passages 60 admit oil from the oil reserve space immediately above in the base casting 1 through tubes 60a which are pro vided to cause the oil to be taken in above the sediment level.

The base casting 1 is machined to locate and mount the bearing plate 50 which is held in position by capscrews 61 and by longer cap-screws 62 which also serve to clamp the pump body 52 and cover 56 in position. Also four cap-screws 62a hold the pump casing parts together but do not enter casting 1, so that the pump assembly may be removed as a unit if desired. An additional nut 46a and lock means 47a are used to hold gear 54 in position. The oil pump assembly above described is closed in by a cover 63, sealed by a gasket 64. Screws 65 and lockwashers 66 hold the cover 63 in position.

The oil pump discharge passage 58 communicates with a passage 68 through a port 50a (Figs. 5 and 6) and the passage 68 delivers oil to an annular space 69 around a valve sleeve 70 which is stationary. Slidably fitted around the upper part of sleeve 70 is a relief valve 71, held down by a spring 72 which bears against a shoulder on valve 71 which is slidably fitted in base casting 1. Fig. 5 shows the valve 71 at its operating point, that is just cracked." If raised slightly from this position by increase in pressure in annulus 69, oil is passed between parts 70 and 71, then through apertures 73, thence around a displacement responsive member 74 and through a perforated spring-seat washer 75 and passages 77 into the chamber 17. Three springs 76 are fitted in three extensions 13a of piston 13 and are proportioned to lift this piston and the weight of the attached parts when there are no pressures in the engine. One of the springs 76 holds the washer 75 seated.

The space in which spring 72 operates is vented to atmospheric pressure through a vent 78, consequently the operation of the valve is controlled exclusively by variations in gage pressure in annulus 69 therefore it functions directly to regulate this pressure and is not influenced by the fact that the escape of oil into chamber 17 as above described provides a useful outlet for this oil, using it at a lower pressure rather than letting it escape to atmospheric pressure. The pump gears 53 and 55 are so proportioned that the quantity of oil delivered is sufficient to keep a small amount of oil passing through valve 71 at all times, but at times when it becomes necessary or desirable to reduce the displacement of the engine the other uses of oil are less than normal so that a larger supply of oil for chamber 17 is always available when expanding of this chamber is necessary. It should be understood that this only insures supplying an adequate quantity of oil to chamber 17, and does not act to control the movement of control member 12 or piston 13, as this is controlled by governing the pressure maintained in the chamber 17 by means of a pressure governed valve which so adequately regulates the rate at which the oil is allowed to escape from this chamber that the rate of oil supply does not have any appreciable efiect on the pressure.

A fitting 79 conveys oil into a tube 80 at the pressure controlled by the valve 71, and oil at this pressure is also admitted to the annular space around a spool valve 81 through ports 82 in sleeve 70. A spring 33 presses down on the valve 81 and its upper end is seated in the displacement responsive member 74. The valve 81 is shown in its cracked position, and the spring 83 is so proportioned that the force it exerts on the valve 81 as it holds this position is varied by vertical movement of member 74 to keep this force proportional to the displacement of the engine. An annular chamber 84 below valve 81 exposes a main portion of the lower area of valve 81 to the pressure of the oil in chamber 84. Since the oil supply pressure is balanced as to its effect on the position of valve 81, and atmospheric pressure is maintained in the chamber above by venting through the center of the valve 81 to its lower end and thence to atmosphere, the position of valve 81 is under the exclusive control of the force applied by spring 83 and the upward force exerted by pressure of oil in chamber 84. When these forces are balanced the valve thus stays in cracked position as shown, while any drop in pressure in chamber 84 causes the valve to be lowered and admit more oil from the high pressure supply to restore a balanced condition, while if the pressure in chamber 84 should become too high the passage from the supply into chamber 84 is entirely closed off and thus the use of oil from chamber 84 returns the balanced condition. Therefore, with adequate supply pressure, the pressure in chamber 84 is maintained proportional to the displacement even under considerable variations in the How of oil permitted from chamber 84.

Passages 85 through sleeve 70 convey oil from chamber 84 into a passage 86 in the base of casting 1, through a port 87 and a cored passage 88 into an annular groove 89 and ports 90 in bearing plate 50. As shaft 42 rotates, the ports 42a therein thus alternately connect the groove 42b With the ports 90 and 51, thereby causing the pressure in groove 42b to vary from atmospheric when connected to ports 51, to a pressure closely approaching the controlled pressure prevailing in chamber 84 when connected to ports 90. A port 91 through the hub of bearing plate 50 connects the groove 42b with a passage 92 through pump body 52 and a passage 93 (Fig. 3) through the pump body 52, hearing plate 50 and base casting 1 to a port 94 in a pad 95.

The fuel pump assembly shown in Fig. 8 is attached to the pad 95 by screws 96. Fuel is supplied from a tank 97 through a tube 98 and a soft synthetic rubber tube 99 which is fastened to a fuel pump body 100 and to the tube 98 by clamps 101. In the pump body 100 is a bellows 102 crimped and hard soldered to a mounting plate 103 which is set into body 100 and sealed with soft solder or oilproof cement 104. 'A light spring in the form of a waved washer 105 supports a ring suction valve 106 against a valve plate 107 having a series of inlet perforations arranged in a circle above the suction valve 106 and another ring of perforations which are covered by a discharge valve 108.

p The working surfaces of valves 106 and 108 and valve plate 107 are preferably lapped smooth and flat, but the flexibility of the valves may be such that they need only be truly flat when pressed into working position by the pressures available in use. The valve 108 is seated by a waved washer spring 108a.

An upper bellows 109 is crimped and hard solder sealed to a mounting piece 110, then mounted in a shell 111, and retained by a lock ring 112. Movement of the free end of the bellows 109 is limited by a stop plate 113 retained by a lock ring 114. This assembly is then sealed under gas pressure by soft soldering a passage 110a. The gas should be non-oxidising and non-condensing at ordinary temperatures such as nitrogen or helium for examples, and the sealed pressure should be somewhat less than the minimum pressure which is to prevail in chamber 84 at minimum displacement. The bellows should be of suitable proportions as related to the compressibility of the enclosed gas to then stand a considerable number of fiexings to the point it will take when the maximum pressure available in chamber 84 is applied in the space surrounding it. The mounting piece 110 is made to fill a large proportion of the space within bellows 109 to reduce the total stroke of the bellows under the range of pressures to which it is subjected in service.

The shell 111 and two gaskets 115 are then clamped between a flanged cap 116 and the pump body by screws 117 and lockwashers 118 thus also clamping a gasket 119 and the valve plate 107. A stop pin 120 is affixed to the valve plate 107 and serves to limit the stroke of bellows 102 to a safe value for a moderate number of cycles. An accumulator check valve 121 is pressed against the top of the shell 111 by a waved washer spring 122, and opens under pressure difference to permit fuel to pass into the 8 discharge opening in the top of flanged cap 116 and through a fitting 123 into a discharge line tube 124.

Referring again to Fig. 5 the smaller diameter portion of the valve 81 is a sliding fit in a spacer 125 which also acts as a lower stop for valve 81 when there is no pressure in chamber 84. A cross slot in the spacer 125 vents the small diameter end of valve 81 to atmospheric pressure through the passage 126 in the base casting 1 into a dry sump space 127. Oil leaking through fits in the valve mechanism as well as miscellaneous leakage in other parts of the unit may be drained into the space 127, particularly from sections where it is desired to avoid excess oil accumulating.

When oil drained into the space 127 reaches a. level above the bottom face of gears 44 and 54 a certain part of this oil runsinto the gear teeth as they are about to mesh, and some of this oil is forced upward against the bottom face of the hub of bearing plate 50 which is in free running contact with the tops of these gears. A port 128 (Fig. 2) is provided in this face just above the closing mesh point of the gears and receives oil at an appreciable pressure. The port 128 communicates with a groove 129 and a port 130 in the bearing plate hub and then through an angular passage 131 which joins a vertical passage 132, which registers with a continuing vertical passage 133 through base casting 1 and bearing plate 50. This chain of passages serves to convey oil from the mesh of the gears up to the top of passage 133 where it flows down into the oil reserve space in the base casting. Any rise in the oil level in space 127 increases this flow, which is adequate to keep the space 127 cleared of all oil except an amount to keep the gears well lubricated.

I have found in practice that an open gear pump of this character will pump more effectively when the gears are helical. Oil trapped in the teeth of helical gears travels axially along the meshing teeth toward the last ends of the teeth to mesh. Since the rotation of shaft 41 is counterclockwise when looking at the top end, the gear 44 has a left hand helix and the gear 54 a right hand helix as indicated by the diagonal lines near the mesh point of these gears in Fig. 2. These helix angles aid the lift of oil and assure quick transfer of oil from the dry sump to the reserve when considerable oil has accumulated in the dry sump after a long period of non-operation.

For similar reasons the transfer of oil from the inlet manifold 59 to the discharge passage 58 is facilitated by having the gears 53 and 55 helical cut at a suitable angle in relation to the direction of rotation.

The chamber 17 is kept supplied with oil by means which have been described and is provided with an outlet port 134 and a pressure governed valve (Fig. 7) comprising a valve shell 135 in which is slidably fitted a valve 136 which is arranged to uncover several large ports 137 when moved downward. The valve 136 is supported on a light spring 138 which is seated at its lower end upon a station ary member 139 which is tightly fitted in sleeve 135 and is prevented from being forced down by fluid pressure by a lock ring 140. The member 139 is axially bored and counter-bored to provide two diameters as shown, and a pilot valve 141, having two corresponding diameters is slidably fitted therein. The valve 141 is pressed downward by a suitably proportioned spring 142 retained by a plug 143 sized for a firm press fit into the upper portion of member 139. An annular passage 144 admits oil from port 134 tocross passages 145 which convey it to an annular space around valve 141 and from there out through ports 1.46 when the pilot valve is at its downward position as shown. This applies the pressure being carried in chamber 17 to the entire lower end area of the valve 136. Vent passages 147 connect the upper side of the shoulder area to atmospheric pressure, so as long as pilot valve 141 remains in the position shown the ports 137 remain covered since the pressure carried in chamber 17 is strongly urging valve 136 upward since it is applied to a larger area below than above this valve.

However if the pressure in chamber 17 rises suificiently this pressure acting on the exposed under area of the larger diameter portion of pilot valve 141 will cause a force upward exceeding the downward force applied by spring 142, moving valve 141 upward to a point where ports 146 are sealed from the supply pressure and act to exhaust oil from under the valve 136 into the space around the lower portion of valve 141. Ports 148 and 149 then convey this oil from there to the general oil reserve. This causes pressure of oil on the exposed upper surfaces of valve 136 to quickly move it down to completely uncover the ports 137 providing an ample outlet from chamber 17.

Since a substantial portion of the force resulting from the pressure on top of the engine pistons 4 is transferred, through apparatus that has been described, to the piston 13 and thus places the oil in the chamber 17 under pressure, a suitable pressure applied to the pistons 4 will cause the valve 141 to act as above described and the ports 137 will rapidly discharge oil until the pressure on the pistons is reduced or the control member 12 has reached its extreme bottom position stopped by resting on the central portion of base casting 1. The port 134 is so positioned that it is only slightly open when the control member 12 and piston 13 reach their bottom position, thus slowing up the last part of the downward travel to avoid shock when the stop is reached. When a suitable pressure on the pistons is exceeded the displacement of the engine may therefore be very rapidly increased, but the rate of decrease is limited by the amount of oil spilled to chamber 17 by the valve 71. The direction of movement of the displacement control member is however determined entirely by whether the pressure in chamber 17 is over or under a certain critical value, with the pressure in chamber 17 in turn determined by the pressure applied to pistons 4.

The pilot valve 141 may hover at a mid-point when the pressure in chamber 17 is being held at a certain value, and then the valve 136 will settle in a position Where the ports 137 are open just sufiiciently to outlet the oil that is being admitted to chamber 17 by the valve 71, thus maintaining the critical pressure.

The average pressure applied to all the pistons 4, which may be called the mean working pressure, depends mainly on the pressure of the air in the intake manifold, and on the amount of fuel being ejected into the cylinders. It depends to some extent on other factors, but the principal other factors are the efiect of engine speed and load on these main factors. Increased load decreases the engine speed and so increases the manifold pressure at a given throttle opening. Since the injection is normally kept coordinated with air weight per cylinder charge to maintain the fuel/ air ratio, the principal means of varying the mean working pressure applied to the pistons is by varying the inlet manifold pressure, either by control of throttling or more indirectly by changing the load on the engine.

The spring 142, governing valve 141 and through it the engine displacement, is made light enough to yield under the pressure in chamber 17 resulting from operation with normal fuel/ air ratio at near atmospheric pressure in the manifold, causing displacement to increase rapidly under this condition, and strong enough to hold valve 141 below its critical point when the mean working pressure on the pistons is suitably and moderately lower, causing the displacement to decrease under this condition. Displacement may be therefore increased by throttle opening or increased engine load, and reduced by reduced load or by closing of the throttle.

Operation at high altitudes would be accompanied by such low atmospheric pressure that the manifold pressure could not be high enough to bring about increased displacement if the above described control means were not provided with atmospheric pressure compensation. This is accomplished by a bellows 150 which is vacuum sealed and soldered to a mounting piece 151 which is threaded into a cap 152 which in turn is threaded into the base casting 1. The valve shell is press-fitted to the cap 152 after the position of the bellows has been suitably adjusted and locked by a nut 153. Passages 154 and 155 are provided through valve 141 to vent its upper end to atmospheric pressure. The bellows and mounting piece 151 being sealed under a vacuum, the upward force applied to the bottom of the valve 141 by the top of the bellows is increased if the pressure in the space around this bellows is reduced. Since this space communicates through ports 148 with the general oil reserve space which is at atmospheric pressure, any drop in the atmospheric pressure prevailing increases the upward force exerted by this bellows. This reduces the oil pressure necessary to hold the pilot valve 141 at its critical operating position against the force of spring 142, thus resulting in a lower pressure being maintained in chamber 17 so that the reduction of the pressure available to apply to pistons 4 due to the reduced atmospheric pressure is compensated by a reduction of the critical pressure governing chamber 17, to thus permit increase or decrease in engine displacement in response to throttle, injection and load, just as when the atmospheric pressure is normal.

The fuel discharge line tube 124 of Fig. 8 leads to the fuel control mechanism shown in Figs. 9, 10, ll, 12, and 13, and is connected by a fitting 156 to the control box 157. A duct 158 drilled in box 157 conveys fuel to an annular groove 159 in a sleeve 160 which has cross-drilled inlet ports 161. A spool valve 162 having a small diameter stem at its upper end is slidably fitted inside the sleeve 160 and is urged upward by a spring 163. A cap 164 is slidably fitted on the stem and press fitted into the upper end of sleeve 160 which also has low pressure outlet ports 165 and controlled pressure outlet ports 166. The spring 163 is preferably so proportioned as to just support the weight of the parts resting upon it, so the effects of this spring and of the weight of the parts may be disregarded in considering the operation of the valve. If no added force is applied to the upper stern of valve 162 any pressure of fluid below will raise it from the position shown, sealing off ports 161 and stopping flow into the valve 162 and opening ports 165 to communicate through the center of the valve 162 with the space below it, reducing the pressure in ports 165 and 166 to substantially zero. On the other hand, if a downward force is applied to the stem of valve 162 the ports 161 are opened, admitting fuel from passage 158 to pass through the passages in valve 162 to increase the pressure ports 166 until an equal upward force is thereby created thus closing ports 161, so it is apparent that the pressure in ports 166 over and above that prevailing in ports 165 can be controlled by the force applied to the stem of valve 162 and that up to the limit of the supply pressure the outlet pressure in port 166 over and above that prevailing in port 165 is substantially directly proportional to the force applied to the stern of valve 162.

With fuel being supplied at substantial pressure in passage 158 the movement of valve 162 required to maintain this outlet pressure difference proportional to the tip plied forces are very small, regardless of the rate at which fuel is used from port 166, within the actual range of used rates. A pasage 167 connects ports 166 with a discharge port 168. Another valve sleeve 170 is fitted 1n the fuel box 157 and a valve 171 is slidably mounted in the upper portion thereof. A small diameter stem 172 on valve 171 is slidably fitted in the lower portion of sleeve 170. Valve 171 also has a small diameter upwardly extending portion which serves to limit its upward motion. A

plug 173 retains the sleeve 170 and serves as an upper stop for valve 171. The smaller diameter bore in the lower portion of sleeve 170 extends through the lower end, and communicates with the passage 167, and also through cross ports 174 and passage 175 communicates with ports 165. A continuation 176 of passage 175 also- 

